chore: Use log level ERROR when logging backend errors with LOG_IF_ERROR

[rmccorm4]

Related PR: triton-inference-server/core#367

1. Use log level ERROR for LOG_IF_ERROR

Before, LOG_IF_ERROR would prefix the line with I for level INFO:

E0605 22:07:23.729999 1135 identity.cc:1175] request 0: failed to get copy buffer, error response sent
I0605 22:07:23.730046 1135 identity.cc:1189] failed setting string parameter: Invalid argument - response was nullptr
I0605 22:07:23.730084 1135 identity.cc:1193] failed setting integer parameter: Invalid argument - response was nullptr
I0605 22:07:23.730123 1135 identity.cc:1196] failed setting boolean parameter: Invalid argument - response was nullptr
I0605 22:07:23.730162 1135 identity.cc:1199] failed setting double parameter: Invalid argument - response was nullptr

After, it uses E for ERROR:

E0605 22:07:23.729999 1135 identity.cc:1175] request 0: failed to get copy buffer, error response sent
E0605 22:07:23.730046 1135 identity.cc:1189] failed setting string parameter: Invalid argument - response was nullptr
E0605 22:07:23.730084 1135 identity.cc:1193] failed setting integer parameter: Invalid argument - response was nullptr
E0605 22:07:23.730123 1135 identity.cc:1196] failed setting boolean parameter: Invalid argument - response was nullptr
E0605 22:07:23.730162 1135 identity.cc:1199] failed setting double parameter: Invalid argument - response was nullptr

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2. Add default TRITON_REPO_ORGANIZATION for building locally.